University of the Aegean, Department of Geography The emerge of Semantic Geoportals Athanasis Nikolaos Konstantinos Kalabokidis Vaitis Michail Soulakellis Nikolaos

University of the Aegean, Department of Geography Agenda Web portals and geo-portals The Semantic Web The emerge of semantic geo-portals Related work Summary & future work

University of the Aegean, Department of Geography The World Wide Web today html web browsers hyperlinks

University of the Aegean, Department of Geography Web Portals Web Portal: A single point of access to information - a library of categorized and personalized content rich organization of information personalized content (customization)

University of the Aegean, Department of Geography Geo-portals Geo-portals: online access to collections of geospatial data rich organization of information rich organization of spatial information interactive GIS mapping

University of the Aegean, Department of Geography How geo-portals work Information providers: publishing GIS data and services Geo-portal: provides the rich organization of GIS data through its GUI GIS user community: searches the portal and exploits data of interest

University of the Aegean, Department of Geography Exploiting geo-data

University of the Aegean, Department of Geography The role of metadata in geoportals Information providers publish metadata (descriptions about the data they want to share) The (catalog) geo-portal organizes the metadata in metadata records Users search the metadata records and exploit data Or view metadata records

University of the Aegean, Department of Geography publishing metadata Submit metadata through GUI Metadata harvesting

University of the Aegean, Department of Geography Geospatial metadata standards American Standard: –CSDGM (Content Standard for Digital Geospatial Metadata) European Standard: –CEN/TC287 (European Committee for Standardization ) EN ISO 19115:2005 Metadata = Identification_Information + {Data_Quality_Information} + {Spatial_Data_Organization_Information} + {Spatial_Reference_Information} + {Entity_and_Attribute_Information} + {Distribution_Information}

University of the Aegean, Department of Geography Current implications Lack of a uniform framework for describing geographic metadata –Deficiency to integrate / publishing metadata in geo-portals Current standards are unable to capture the data semantics they describe Semantic heterogeneity –Semantic conflicts in modeling - terminology (i.e. homonyms, synonyms) –Insufficiency of XML (GML) to solve semantic discrepancies

University of the Aegean, Department of Geography The Semantic Web rich semantic organization –ontologies (description schemata) RDFS, OWL –resource descriptions RDF navigation based on conceptual relationships –semantic hyperlinks

University of the Aegean, Department of Geography …and the geospatial Semantic Web Development of spatial ontologies and with a formal semantics Classification of geo-data under the appropriate classes of the ontologies Processing of geospatial queries against these semantic ontologies

University of the Aegean, Department of Geography title Metadata catalogs of a Semantic Geo- Portal in RDF belongsToTheme Enumeration live data Downloadable documents ArcIMS service Documents Static documents Map File downloadable content “….” “…” “vector” publisher description on-line linkage spatial info Metadata record Feature serviceImage service related content serverURL String title String Enumeration publisher description on-line linkage spatial info &r1 &r2 &r3 related content r1: downloadable content &r4 r2: r3: r4: belongsToTheme Natural Disasters serverURL “…” belongsToTheme Natural Disasters serverURL “…” String file size “…” file size

University of the Aegean, Department of Geography Semantic navigation through –hierarchies of classes/properties –concept relationships –resources relationships semantic querying –data/schema querying –filtering conditions representation of geo-data –Mapping –Live data maps (Web Map Service- WMS) Publishing/representation of metadata according to spatial ontologies Requirements for semantic geo- portals

University of the Aegean, Department of Geography expresses the semantic meaning of the geospatial resources using RDFS ontologies and RDF resource descriptions exploits a declarative query language (RQL) to resource descriptions –filtering –on demand construction of RQL queries according to user navigation in the schema/data Our solution

University of the Aegean, Department of Geography Examples: Find all image services about natural disasters as well as related documents about them: Find the descriptions of the Map Files that you can download: Our solution [cont] select X1,X2 from {X1;Image_Service}related_content{X2;Documents}, {X1;Image_Service}belongsToTheme{X3} where X3 = “Natural Disasters” select W from {;Map_Files}downloadable_content{X2;Downloadable_Documents}, {;Metadata_record}description{W}

University of the Aegean, Department of Geography –Uses open source map tools MapTools (image server) WMS (GIS services) php + apache (web server) –Provides customization capabilities through the portlet framework of Jetspeed Our solution [cont] portlets: pluggable, reusable components of portal

University of the Aegean, Department of Geography Related work Semantic portals: ICS-FORTH Portal demo geo-portals: Geospatial-One-Stop

University of the Aegean, Department of Geography Summary Portals, geo-portals, metadata catalogs The current organization in geo-portal’s metadata catalogs is unable to capture the semantics of the data being described Semantic geo-portals: organize their resources according to geospatial ontologies exploit semantic query languages (RQL) to provide access to information resources corresponding to the user’s navigation paths.

University of the Aegean, Department of Geography Future Work Development of the appropriate geo- ontologies Design of the geo-portal system

University of the Aegean, Department of Geography Thank you